Under current motor vehicle safety standards automotive vehicles are tested in a 50 MPH 70% offset Moving Deformable Barrier (MDB) rear impact test. The test is intended to test fuel system integrity in a rear-end collision. In the test procedure, 70% of the rear of the vehicle is impacted by a 1,368 kg deformable barrier at 80 km/h.
An important factor in passing the MDB test is providing sufficient crush space in the vehicle to absorb the force of the impact. One possible solution is to reduce the volume of the fuel tank but this is undesirable because it reduces the range of the vehicle between refueling. In many vehicle designs a spare tire is attached to the vehicle below the rear trunk floor. The spare tire reduces the available crush space and results in additional deformation, higher plastic strain and increased pressure applied to the fuel tank. The spare tire is usually laterally squeezed in the crush zone in the MDB test and reduces the available crush space.
Referring to FIG. 1, a rear rail “R” of a vehicle is illustrated in a side elevation view. The rear rail is aligned at the same height as the crush cans “C” and rear bumper “RB” and is approximately 137 mm above the frame “F” at the passenger compartment. This arrangement causes the spare tire to be laterally squeezed in the MDB test.
This disclosure is directed to solving the above problems and other problems as summarized below.